Auckland Regional Public Health Service clinical director Julia Peters said the Melbourne laboratory was giving the testing its highest priority.

About 100 people are in quarantine as they wait for the Melbourne results.

Health officials were still trying to contact 18 of the 364 passengers that traveled with the group on Air New Zealand flight NZ1, which arrived in Auckland from Los Angeles on Saturday at 5 a.m.

A team of about 25 people had been working on tracing travelers.

All would be offered the flu medicine Tamiflu and asked to stay at home for several days and those they had had contact with would be dealt with as well, Ryall said.

In a related development, three people from Auckland's Northcote College who returned to New Zealand at the weekend after visiting Mexico were cleared of influenza A on Tuesday morning.

The trio had been exhibiting flu-like symptoms and there were fears they may have been infected.

Potential swine flu cases are also being monitored nationwide, including in Auckland, Hamilton, Nelson, Canterbury and Otago.

Health officials are now screening all passengers arriving in New Zealand from North America.

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Editor:Yang Jie